Devices of this type are used, in particular, in surface technology, for example, of the automotive industry, for conveying paint powder to an application device, for example, a rotary atomiser. Different types of pumps can be used.
For example, a partial vacuum is generated by means of piston pumps known per se, whereby the paint powder fluidised in a receptacle is aspirated and conveyed to an atomiser in order to be applied thereby to an object, for example, a vehicle body.
In this case the paint powder is conveyed while being subjected to strong mechanical action, so that heating and abrasion of the individual powder particles, against either one another or the wall of the pump, cannot be completely avoided. This can result in an unwanted change in the particle size distribution of the paint powder. In addition, the abrasion can cause contamination of the pump or the powder conduits and even clogging of the entire plant.
Positive displacement pumps are also used for conveying powdery fluidized media. However, these pumps are less suited to paint powder because the paint powder tends to agglomerate when at rest and can therefore clog a positive displacement pump after a period of stoppage.
The susceptibility of such pumps to clogging with paint powder results partly from the fact that they have a relatively large number of comparatively small components which move quickly during operation of the pump, and which are spaced from one another, even if only by a small distance. A large number of gaps are therefore present in the flow path of the fluidized medium, in which gaps the medium may be deposited, impairing the operability of the pump and reducing the conveying capacity of the device.
The present invention is directed to addressing these and other concerns.